From owner-freebsd-hackers Tue Sep 26 18:22:10 1995 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id SAA21358 for hackers-outgoing; Tue, 26 Sep 1995 18:22:10 -0700 Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id SAA21329 for ; Tue, 26 Sep 1995 18:21:56 -0700 Received: from sax.sax.de by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id CAA11376; Wed, 27 Sep 1995 02:21:47 +0100 Received: by sax.sax.de (8.6.11/8.6.12-s1) with UUCP id CAA12172; Wed, 27 Sep 1995 02:21:47 +0100 Received: (from j@localhost) by uriah.heep.sax.de (8.6.12/8.6.9) id VAA15240; Tue, 26 Sep 1995 21:31:00 +0100 From: J Wunsch Message-Id: <199509262031.VAA15240@uriah.heep.sax.de> Subject: Re: SLIP and DNS problem To: radova@risc6.unisa.ac.za (A. Radovanovic) Date: Tue, 26 Sep 1995 21:30:59 +0100 (MET) Cc: hackers@freebsd.org Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) In-Reply-To: <9509260912.AA51193@risc6.unisa.ac.za> from "A. Radovanovic" at Sep 26, 95 11:12:23 am X-Phone: +49-351-2012 669 X-Mailer: ELM [version 2.4 PL23] MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Content-Length: 1569 Sender: owner-hackers@freebsd.org Precedence: bulk As A. Radovanovic wrote: > > I have 8 modems connected to my BSD system. From time to time, after login, > the SLIP client can't get host name resolved, or can't get it resolved on > some of the lines. When I reboot the machine everything is OK for some time. > > It seems that the server doesn't know the client's IP. I think that the DNS > works fine - it resolves names, answers ping, ftp, www, telnet,... > I'll appreciate it very much if somebody can give me a clue. The server must always know the client's IP for SLIP (since it's not negotiated). It rather looks like the infamous "stale clone route" problem. This happens if a line breaks with active connections on it. Subsequent packets arriving for the IP address of the client whose line just broke will not hit any host-specific route, and therefore will be resolved via the default route, usually pointing back to the ethernet. This causes a "clone route" to be allocated for this particular IP host (you can see them with "netstat -ra"), and a subsequent login attempt of the client causes the weird message "File exists" to appear at ifconfig time of the SLIP interface (translate this into: "Route exists"). The only known workaround by now is to delete any potential host route to the intented new host address right before configuring the SLIP interface. It works for sax.sax.de now this way (yes, i've been complaining about this problem before). -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ Never trust an operating system you don't have sources for. ;-)